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What is a lateral collateral ligament (LCL) injury?

The lateral collateral ligament (LCL) is the ligament located in the knee joint. Ligaments are thick, strong bands of tissue that connect bone to bone. The LCL runs along the outside of the knee joint, from the outside of the bottom of the thighbone (femur) to the top of the lower-leg bone (fibula). The LCL helps keep the knee joint stable, especially the outer aspect of the joint.

An injury to the LCL could include straining, spraining, and partially or completely tearing any part of that ligament. According to Orthogate, the LCL is one of the more commonly injured ligaments in the knee. Because of the location of the LCL, it’s common to injure the LCL along with other ligaments in the knee.

The main cause of LCL injuries is direct-force trauma to the inside of the knee. This puts pressure on the outside of the knee and causes the LCL to stretch or tear.

Symptoms of an LCL injury can be mild or severe, depending on the severity of the sprain or if it’s torn. If the ligament is mildly sprained, you may not have any symptoms at all. For a partial tear or complete tear of the ligament, your symptoms may include:

  • swelling of the knee (especially the outer aspect)
  • stiffness of the knee joint that can cause locking of the knee
  • pain or soreness on the outside of the knee
  • instability of the knee joint (feeling like it’s going to give out)

To diagnose an LCL injury, your doctor will examine your knee and look for swelling. They’ll also move your knee in various directions to determine where your pain is and how severe your symptoms are.

If your doctor believes you may have a torn ligament, you may undergo imaging tests like X-rays or MRI scans. These tests will allow your doctor to see the soft tissues inside the knee.

The treatment options for LCL injuries will depend on the severity of the injury and your lifestyle.

For minor injuries, treatment may include:

  • splinting
  • applying ice
  • elevating the knee above the heart
  • taking a pain reliever
  • limiting physical activity until the pain and swelling are gone
  • using a brace (knee immobilizer) or crutches to protect the knee
  • physical therapy or rehabilitation to strengthen and regain range of motion

For more severe injuries, treatment may also include physical therapy, rehabilitation, or surgery. Physical therapy strengthens and helps you regain range of motion. Surgery may include ligament repair or reconstruction.

Surgery doesn’t usually treat injuries to only the LCL. However, the LCL is often injured along with other ligaments in the knee. In these cases, surgery is probably necessary.

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It’s difficult to prevent knee ligament injuries because they’re often a result of an accident or unforeseen circumstance. However, several preventive measures can help minimize the risk of a knee ligament injury, including:

  • using proper technique and alignment when doing physical activities, including walking
  • stretching regularly to maintain good range of motion in the body
  • strengthening the muscles of the upper and lower legs to help stabilize the joint
  • using caution when playing sports where knee injuries are common, such as soccer and football

For minor injuries, the ligament may heal without any issue. However, it’s important to note that if the ligament got severely stretched, it may never regain its prior stability. This means that it’s more likely that the knee will be somewhat unstable and you could easily injure it again. The joint could become swollen and sore simply from physical activity or minor injury.

For those with a major injury who don’t have surgery, the joint will most likely remain unstable and easily injured. You may not be able to do physical activities that require repetitive use of the knee, including running, climbing, or biking. Pain could result from minor activities like walking or standing for extended periods. You may have to wear a brace to protect the joint during physical activity.

For those who have surgery, the outlook will depend on the severity of the original injury and the surgical procedure. Generally, you’ll have improved mobility and stability after the joint completely heals. You may have to wear a brace or limit physical activities in the future to help prevent reinjuring the knee.

In knee injuries involving more than just the LCL, treatment and outlook may be different, as those injuries could be more severe.